1. Field of the Invention
The present invention relates to an information output unit that outputs information to a liquid crystal display unit and an electronic apparatus including such an information output unit.
2. Description of the Related Art
In recent years, as represented by a cellular phone, an electronic apparatus including an information output unit that outputs information to the liquid crystal display unit and a liquid crystal display unit that displays an image based on the information inputted by the information output unit is widely used. In this specification, the liquid crystal display unit includes an LCD (Liquid Crystal Display) panel, a source driver, and a gate driver and displays the image based on the information inputted by the information output unit.
Since a gamma characteristic (a characteristic representing a relation between a gradation voltage and luminance of an LCD) of the LCD panel is different for each type of the LCD panel, in displaying an image using the liquid crystal display unit, it is necessary to apply gamma correction suitable for the LCD panel in use to original image information. Therefore, in replacing the type of the LCD panel of the liquid crystal display unit with another type, it is necessary to change a setting concerning gamma correction.
In the past, when the type of the LCD panel of the liquid crystal display unit is replaced with another type, the setting concerning gamma correction is changed by performing operation such as replacement of a ROM and readjustment of a circuit of the liquid crystal display unit. However, these kinds of operation are extremely complicated. Thus, various inventions for solving this problem have been made. An example of the inventions is found in JP-A-10-333648 (hereinafter, “Patent Document 1”).
Patent Document 1 discloses a liquid crystal display unit that can change gamma correction information according to an LCD panel by storing information concerning a reference voltage of a gamma correction circuit in a memory and extracting the information, and D/A-converting the information to generate the reference voltage.
In the electronic apparatus including the information output unit and the liquid crystal display unit, the liquid crystal display unit may be replaced. Some liquid crystal display unit displays an image based on image information inputted by the information output unit without applying gamma correction to the image information (hereinafter, “first liquid crystal display unit”). Another liquid crystal display unit displays an image based on image information inputted by the information output unit after applying gamma correction based on gamma correction information inputted by the information output unit to the image information (hereinafter, “second liquid crystal display unit”).
Therefore, when the information output unit is connected to the first liquid crystal display unit, the information output unit needs to apply gamma correction suitable for display of an image by the first liquid crystal display unit to an original image information and output image information obtained after gamma correction. On the other hand, when the information output unit is connected to the second liquid crystal display unit, the information output unit needs to output original image information and gamma correction information suitable for display of an image by the second liquid crystal display unit. In other words, information that the information output unit needs to output is different when the information output unit is connected to the first liquid crystal display unit and when the information output unit is connected to the second liquid crystal display unit.
Therefore, in the past, the information output unit changes, by performing replacement of a ROM, readjustment of a circuit, and the like, information to be outputted or changes information to be outputted in terms of software. In this way, the information output unit can output information to the liquid crystal display unit connected to the information output unit regardless of whether the liquid crystal display unit is the first liquid crystal display unit or the second liquid crystal display unit.
However, when the information output unit changes, by performing replacement of a ROM, readjustment of a circuit, and the like, information to be outputted, operation in replacing the liquid crystal display unit is extremely complicated. When the information output unit changes information to be outputted in terms of software, a large-capacity memory, a large number of D/A converters, and the like are necessary. Therefore, for example, a size of an apparatus is increased and power consumption is increased because of complication of a software routine.
The invention disclosed in Patent Document 1 can make it unnecessary to perform operation in replacing a type of the LCD panel of the liquid crystal display unit. Nevertheless, the invention cannot solve the problems of the information output unit connectable to both the first liquid crystal display unit and the second liquid crystal display unit.